An easy method of fabricating superoleophobic surfaces on Al substrates by constructing reentrant structures is reported. The reentrant microanometer-scale structures comprise micrometer-scale, rectangular-shaped, and step-like Al structures obtained by electrochemical etching and nanometer-scale Ag grains resulting from immersion in [Ag(NH3)2]~+ solution. Surface energy is reduced by perfluorooctanoic acid (PFOA) containing -CF3 and -CF2- groups. The PFOA-modified microanometer-scale rough structures enable the formation of a composite solid-liquid-air interface with peanut oil. These structures show good superoleophobicity with a peanut oil contact angle of 160.0 ± 2° and a sliding angle of 8°. Nanometer-scale structures can effectively transform the micrometer-scale non-reentrant structures into reentrant structures. With the aid of suitable low surface energy materials such as PFOA, fabricating superoleophobic surfaces on Al substrates can be easier.
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